The present invention relates to the frequency synthesizer art and, in particular, to a frequency synthesizer for use as the frequency controlling circuit in a radio transceiver.
Frequency synthesizer designs are well known, especially in the communication art. When used in combination with radio transmitters or receivers, the synthesizer produces any one of several oscillating signals, each of which is at a desired frequency for proper transmitter or receiver operation. A particularly useful feature of synthesizers is that they may be programmed to operate in discrete frequency steps. This allows tuning of the receiver or transmitter to a multitude of selected frequencies, thus allowing multichannel operation.
A fundamental problem with synthesizer designs is that they have been relatively expensive to produce. This is due to the large number of components required, along with the manufacturing costs for the total assembly. A reduction in the number and cost of components has often resulted in a sacrifice in frequency accuracy, which is especially undesireable in applications wherein the synthesizer controls a radio frequency transmitter.
A particularly useful application for synthesizers would be in citizens band transceivers wherein a user may wish to operate on any one of 23 channels. Due to the aforementioned prohibitive cost of synthesizers, however, very few synthesizers have found use in citizens band equipment.